The present invention relates to a fuel injector electromagnetic metering valve.
The metering valves of fuel injectors generally comprise a control chamber with a drain conduit normally closed by a shutter which, in known metering valves, is normally closed by the armature of an electromagnet, and is released to open the conduit by energizing the electromagnet so as to move the armature towards the core of the electromagnet.
As is known, the main parameter for evaluating the efficiency of a metering valve is the maximum permissible operating frequency, which depends on the speed with which the valve responds to a command to open or close the drain conduit, and hence on the speed with which it responds to energizing or de-energizing of the electromagnet.
The electromagnets of known metering valves generally present two coaxial pole pieces defining a seat for a cylindrical coil; while the armature is in the form of a disk for closing the magnetic circuit of the core, and which must therefore present a diameter substantially larger than the outside diameter of the core coil seat.
Metering valves of the aforementioned type present several drawbacks. In particular, the disk presents a large section resulting in considerable hydraulic resistance, parasitic currents, and a mass in turn resulting in considerable inertia; while, to achieve the necessary response, operation of the armature requires a strong return spring on the one hand and, on the other, an electromagnet capable of generating considerable electromagnetic force and, hence, having a large number of turns and/or a high energizing current.